Purpose: To compare the retention forces of implant overdenture patrices (ball, bar, and TiSi.snap) to conventional (O-ring, metal housing, and plastic clip) and polyvinyl siloxane (PVS)–based silicone (Retention. sil 200, 400, and 600; Mucopren Soft; and GC Reline Soft) matrix materials.
Materials and Methods: Two implant analogs in which the patrices were to be placed were embedded parallel to each other in polyethylene blocks, and the matrices were placed in heat-polymerized acrylic blocks that were fabricated as overdentures. Ten samples were prepared for each attachment type, and 180 samples were obtained from 18 groups. All samples were placed in a chewing simulator for occlusal force application and for insertion and removal of the pieces. Retention measurements were performed with a universal testing device at the initial (10 cycles), simulated first-year (1,825 cycles), and simulated second-year (3,650 cycles) periods, assuming that the patients would insert and remove their overdenture five times daily.
Results: Loss of retention occurred in all of the attachment systems at the end of 3,650 cycles (P < .05). The PVS matrix materials showed less retention than the O-ring and metal matrices when a ball patrix was used, while they had higher retention than clips when the Hader bar patrix was used (P < .05). Among the PVS matrix materials, Retention.sil 200 produced the lowest retention values, whereas Retention.sil 600 generated the highest.
Conclusion: PVS matrix materials showed higher retention than achieved by yellow plastic bar matrices; however, these materials exhibit lower retention than plastic and metal matrices with ball abutments.
